In the absence of a regional thermal gradient, does the Viburnum Trend fit into a common regional hydrologic flow model with other Ozark region MVT deposits

A popular misconception is that a regional thermal gradient (deduced from fluid inclusions in sphalerite) exists among the MVT districts of the Ozark region, apparently linking them to a common regional hydrologic flow model with an Arkoma Basin fluid source. Examination of all available data indicates that there is no thermal gradient in the Ozark region MVT deposits. Means and ranges of T[sub h] data for fluid inclusions in sphalerite from the Northern Arkansas (NA), Tri-State (TS) and Viburnum Trend (VT) districts are statistically indistinguishable from one another. Th values from sphalerite in NA, TS and VT appear bimodal. Unimodal th values for CM appear to correspond to the lower T[sub h] mode of the other districts. It is notable that the lower T[sub h] mode for the VT represents Early and Late Stage sphalerite, whereas the higher T[sub h] mode represents Main Stage sphalerite. In the absence of a regional thermal gradient in the Ozark region, the most useful tools to link (or separate) MVT districts are geochemical data. There may be a connection among the NA, TS and CM districts, based on similarities of ore and gangue mineralogy and geochemistry, including trace element data for sphalerites, K/Cl andmore » Ca/Mg ratios of inclusion fluids, and lead and sulfur isotopes. Minor, Late Stage mineralization in the Viburnum Trend district also shows geochemical similarities to the other districts. However, predominant, Main Stage mineralization in the Viburnum Trend is anomalous in its mineralogy and geochemistry. In the absence of a regional thermal gradient, the Viburnum Trend does not fit easily into a common regional hydrologic flow model with other Ozark region MVT deposits.« less